The ichthyotoxin produced by the red-tide dinoflagellate Gymnodinium breve, purified by high performance liquid chromatography, will be analyzed by C13-nuclear magnetic resonance. Following enzymatic and chemical fragmentation, analyses by gas-liquid chromatography, infrared spectroscopy and mass spectroscopy will be performed to establish the chemical structure of the parent compound. The interaction of the hemolysins produced by G. breve and Pymnesium parvum with lipid bilayers and liposomes will also be studied to determine their specificity against known phospholipids and channel-forming compounds.